note the WorkspaceView tests and the TrafficLights defect in §9

docs/workspace-panel-todo.md

@@ -1010,6 +1010,31 @@ they are marked below, because a dead-code list that is itself wrong is the wors
       now registered in `test-setup.ts`, where preload's lack of a file scope makes it global. Adding
       one test file broke fourteen assertions in `DataTable.test.tsx` before both were understood.
 
+- [x] **`WorkspaceView`, and the second consecutive bug a test found that review had not.** _(`bfa9967`,
+      branch `agent-coordination-mvp`)_ — 11 tests over the last untested mutator, driving the real
+      `WorkspaceView` through the real `WorkspaceRenderer` and `PanelSlot`, so the buttons under test
+      are the buttons. Two properties: every layout write is an *updater* rather than a computed tree
+      (two of the paths are deferred — the 500 ms resize debounce, and a window resize firing `onLayout`
+      on every group at once — so a computed tree silently undoes the write before it and resurrects an
+      older `config`); and `usePanelClose` fires on close *intent* only, never on the unmounts a drag,
+      a swap or a mobile switch cause.
+      Four of the eleven failed on the first run, all on one defect. `TrafficLights` took `onRemove`
+      **and** `isLastPanel` and used `isLastPanel` only to pick the tooltip: the red button read "Close
+      panel" and called `onClearApp` regardless, so closing a panel from its own chrome was impossible —
+      the panel stayed, emptied, and the context menu was the only path that worked. Introduced by
+      `25f5f74`. Cosmetic before identity lived in the layout; not now, because clearing the app drops
+      the `config` that named the panel's agent while the panel survives to be renamed by whatever is
+      put in it next. The pin is "a panel that is NOT the last is removed".
+      One hardening came out of the same pass, and it stands on its own merits: the ephemeral pane's
+      sizing effect now try/catches. `react-resizable-panels` **asserts** rather than no-ops when asked
+      to size a group it has not laid out yet, and an assert thrown from an effect aborts the commit —
+      trading a file preview's geometry for the whole dashboard. Also worth recording as method: the
+      assert fires in happy-dom (no layout, so the group's size array never populates) and **not** in a
+      real browser — measured, six panels on `/dashboards`, empty console — and a `ResizeObserver` +
+      `getBoundingClientRect` stub written to "fix the environment" turned out to fix nothing. The
+      try/catch was the whole difference, and the stub was deleted rather than left behind as a comment
+      claiming credit for it.
+
 - [x] **A panel is told where it is, instead of being handed a key to reverse-engineer.** _(`dbe585f` +
       `717580f` + `585f234`, branch `agent-coordination-mvp`)_ — the first three items of §5.9. The
       context field `dashboardId: string` — which was never an id, always the whole `workspace.key` —